Bright spark dev irons out light interference

Dusts off unused 'paperweights' to save data entry program

On Call Dust yourselves off, dear readers, it’s Friday once more and time for On Call, our weekly column of reader’s technical triumphs.

This week, “Justin” has written in to tell El Reg about the time he worked as the lone software developer at a foundry.

By all accounts, it was a dirty job if you ever left the confines of the office spaces. "You only had to go to the shop floor briefly to spend the rest of the day stinking of dust and metal," he recalled.

One of the systems he built while there was a data capture program for the shop floor – "basically a mini-PC in a sealed IP65 box with a touch screen built into the front door, to try and protect it all from the dusty conditions, and various attachments dangling out from the bottom.”

The system worked pretty well, Justin said, but for reasons he couldn’t fathom, he got a call about once a week saying that the screen either wasn’t responsive or the user had needed to hard reset the box to get it working again.

“The only accessible switch was on the wall for the power, and the bios was set to turn on when power was restored. Thankfully, Windows 7 didn’t mind too much being rebooted this way regularly.”

After this had been going on for some time, Justin arrived into work one morning to find a message saying it had gone down again.

Having a bit of time, he braved the shop floor, heading through the darkened foundry to the box, in a bid to figure out what was going on.

“Someone must have rebooted it, because as soon as I touched the black screen, it lit up and I was navigating around the interface as normal,” Justin said.

Fed up with having got dusty and smelly for no apparent reason, Justin thought he’d do something constructive while he was there, like check Windows updates.

But first, he hit the wall-switch to turn the lights on. “Then, a dozen low overhead strip-lights suddenly banished the darkness… and the screen.”

All of a sudden, the screen had stopped responding. Justin rebooted and repeated his efforts, but the same thing happened again.

Musing on the problem, our dusty hero thought it might be interference – but couldn’t figure out how to fix it without moving the machine, which wasn’t feasible without re-working the layout of the entire area.

Then he had a thought. “In the old days, USB printers used to come with separate ferrite blocks to the cables,” Justin said. “I’d never used them, but had a vague recollection they reduced interference.”

Even better, the company’s IT team had accumulated dozens over the years, and so Justin grabbed one, looped the USB cable for the touchscreen through it a few times and tested the setup again.

“I was slightly amazed to find it worked perfectly after that – it was never again affected by the lights,” Justin said. “I also discovered a new respect for the useless paperweights that used to be supplied with printers.”

Have you ever put something apparently useless to good use? Has a co-worker ever chucked out something that might have been useful? Tell On Call your tales of make-do-and-mend, and you might see your pseudonym gracing next week’s column. ®